Threaded-group piles are widely used in clay, silt, and sand formations owing to their high bearing capacity. However, current research on threaded piles mainly focuses on single piles, and the group pile effect and variable cross-section effect have not yet been sufficiently investigated. In this study, the group pile effect of threaded group piles with different pile numbers, spacings, and lengths and the variable section effect of threaded single piles were investigated using a model test combined with the digital image correlation (DIC) technique. This study shows that: (1) the maximum vertical and horizontal displacements of sandy soil around the threaded ring occur at the threaded ring and its lower notch, respectively. The greater the number of threaded rings, the greater is the value-added bearing capacity and the smaller is the benefit of the increase, and the mechanism of the variable section effect of a threaded pile is closely related to the development of its damage surface. (2) The horizontal displacement between group piles increases and then decreases in the process of pile compression, and the vertical displacement is transferred from the top to the bottom of the arch. At the end of pile pressing, the vertical displacement vectors of the sand between the group piles are superimposed on each other, and the horizontal displacement vectors are weakened by each other. (3) The group pile effect increases with an increase in the pile number and pile length. As the pile distance increased, the pile side and pile end resistances gradually became stronger, and the group-pile effect decreased. The larger the settlement, the smaller is the group pile effect, which reveals the interaction mechanism between the soil and threaded pile and provides a theoretical basis for improving the bearing performance of threaded group piles.
YANG Jiaxiang
,
LU Ye
. Macro and micro study on pile effect and variable section effect of threaded pile group in sand stratum[J]. Journal of Shanghai University, 2026
, 32(4)
: 753
-768
.
DOI: 10.12066/j.issn.1007-2861.2567
[1] 蔡鹏. 南沿江城际高速铁路挤密螺纹桩复合地基承载特性研究[D]. 南京: 南京林业大学, 2022.
[2] 孔德志. 注浆成型螺纹桩施工工艺及承载特性试验研究[J]. 建筑施工, 2014, 36(12): 1327-1329.
[3] 孙文怀, 张元冬, 魏厚峰, 等. 螺纹桩在软弱地层中的应用[J]. 华北水利水电学院学报, 2009, 30(3): 74-76.
[4] 吴敏, 李波扬. 全螺旋灌注桩——螺纹桩竖向承载力初探[J]. 武汉大学学报(工学版), 2002(5): 109-112.
[5] 李成巍, 陈锦剑, 吴琼, 等. 灌注螺纹桩承载机理与计算方法[J]. 上海交通大学学报, 2010, 44(6): 726-730.
[6] 冯浙. 砂土地基中螺杆桩竖向承载特性的模型试验研究[J]. 建筑科学, 2019, 35(5): 97-102.
[7] 周杨. 变截面螺纹桩复合地基竖向承载特性研究[D]. 西安: 西南交通大学, 2015.
[8] 陈亚东, 于艳, 董云, 等. 竖向受荷螺杆桩工作性状试验研究[J]. 地下空间与工程学报, 2022, 18(3): 860-867.
[9] Wei H M, Li L, Peng W, et al. Calculation method and mechanism of ultimate side resistance of screw pile [J]. Marine Georesources Geotechnology, 2023, 41(1): 99-113.
[10] Manh H H, Anwar A M, Jiro K, et al. Experimental and numerical study on pressure distribution under screw and straight pile in dense sand [J]. International Journal of Geomechanics, 2022, 22(9): 04022117.
[11] 赵志明. 螺纹桩竖向承载特性及群桩效应研究[D]. 杭州: 浙江工业大学, 2019.
[12] 杨启安, 沈保汉. 螺纹桩承载机理及承载力计算方法[J]. 工业建筑, 2013, 43(1): 67-70.
[13] 姜赟, 陆烨, 唐侨楚, 等. 非接触测试技术在模型沉桩试验中的应用[J]. 岩土工程学报, 2020, 42(S1): 208-213.
[14] 姜赟, 陆烨, 王校勇. 基于数字图像技术的静压桩周土体位移规律分析[J]. 上海大学学报(自然科学版), 2021, 27(6): 1118-1127.
[15] Bolton M D, Gui M W, Garnier J, et al. Centrifuge cone penetration tests in sand [J]. Geotechnique, 1999, 49(4): 543-552．
[16] Azaam W R, Elwakil A Z. Modelstudy on the performance of single-finned pile in sand under tension loads [J]. International Journal of Geomechanics, 2016, 17(3): 04016072.
[17] 张嘎, 张建民, 梁东方. 土与结构接触面试验中的土颗粒细观运动测量[J]. 岩土工程学报, 2005(8): 903-907.
[18] 周敏明, 钱建固, 黄茂松, 等. 注浆成型螺纹桩桩土接触面机制的离散元模拟[J]. 岩土力学, 2016, 37(S1): 591-595; 608.
[19] 方崇, 张信贵, 彭桂皎. 对新型螺杆灌注桩的受力特征与破坏性状的探讨[J]. 岩土工程技术, 2006(6): 316-319.
[20] 张哲伦, 陈海兵, 俞峰, 等. 桩身变截面效应对异型摩擦桩承载性能的影响分析[J]. 浙江理工大学学报(自然科学), 2023, 49(5): 651-663.
[21] 龙涛. 螺纹桩与土相互作用研究[D]. 长沙: 中南大学, 2012.
[22] 王国才, 束炜, 赵志明, 等. 竖向荷载作用下螺纹群桩承载特性和群桩效应研究[J]. 浙江工业大学学报, 2022, 50(3): 290-298.
[23] 陈亚东, 王安汀, 蔡江东, 等. 竖向受荷螺杆桩承载变形特性模型试验[J]. 施工技术, 2017, 46(14): 116-119.
[24] 冷伍明, 魏广帅, 聂如松, 等. 螺纹桩竖向承载特性及承载机理研究[J]. 铁道工程学报, 2020, 37(5): 1-6; 35.
[25] 常远. 不同桩距桩基础在竖向荷载作用下沉降性能研究[D]. 开封: 河南大学, 2019.
